1. Field of the Invention
The invention relates to a universal flexible sheath with bellows for an articulated joint and a device for insalling the same.
The invention relates to the industrial and commercial area of the manufacture and distribution of equipment for motor vehicle repair and maintenance shops. The sheath is used for protecting lubricated joints such as universal joints, constant velocity joints, three-ball-and-trunnion universal joints, ball joints, socket joints, or similar joints used for transmitting movement to mobile members. The installiation device can be adapted to all types of protective sheaths, and particularly to those used for mechanical transmission components such as steering racks.
Protective sheaths for articulated joints serve for protecting the articulations against foreign bodies, impacts and other external elements. They also serve to contain in a leakproof manner, the lubricating mass that the mechanism needs in order for it to last.
The sheath utilizes by a tubular element made of rubber or flexible elastomer, which can be conventionally molded in a single piece and formed of a conical central part having ridges that permit flexing and axial extension of the body. The tublar element has two ends, each having cylindrical fixing zones with an inner diameter enabling the ends to be attached to the corresponding components of the articulated joint. The ends will also utilize grooves which act as forming seats intended for receiving clamping devices so as to ensure the leak tightness of the assembly.
2. Description of Background and Relevant Information
Most sheaths are specific for each application, particularly for outfitting new vehicles. In order to reduce the number of references on the replacement market, some models are "universal", i.e. they can be mounted on a wide range of articulated joints having different diameters and lengths. This "universality" is achieved, specifically, by means of multiple, stepped fixing zones, as disclosed in patent document EP 0 339 387, for example, which relates to a protective bellow for the articulated joints of a mechanical transmission. The sheath utilizes several fixing zones of different diameters at each end.
In use, the protective sheaths are subject to constant distortion in length and inclination, while also being subject to rotations of very variable speed. Under the effect of centrifugal force and distortion of the wall of the sheath, the lubricating substance tends to migrate away from the parts of the joint near the axis of rotation and the articulation mechanisms, which, in case of leakage or improper filling, may seriously compromise the functioning or life of the joint.
In the case of replacement sheaths, and in order to avoid disassembling the transmission assembly, installing the protective sheaths in its proper position is generally done by means of a rigid hollow mounting cone with or without expander rings, such as those described in patent document FR 2 727 644. This reference presets a sheath installing device comprising a hollow cone whose base may be expanded as needed by means of a series of conical rings mounting up on the cone, the dimensions of which correspond to the different diameters of the articulated joints to be equipped with a protective sheath.
The base of the cone is placed around the spherical mounting or "bowl" that is the largest diameter element of the articulated joint, onto which the bellow is slid by forcing so as to move it far enough for its widest end to come into position on the periphery of the element. In this manner, the cone serves to facilitate the intense stretching that the bellows must undergo. When it reaches the end of the cone, the sheath retracts suddenly to assume a position on the proper side of the bowl or spherical mounting.
These conventional cones are both rigid and cumbersome; they require different diameters depending on the universal joints found in the market, and are, therefore, relatively expensive.